Mycotoxins are toxins produced by fungi that contaminate grains and nuts. These toxins cause immunosuppressive, carcinogenic, cytotoxic and teratogenic effects in humans and animals who consume the contaminated grains and nuts. Aflatoxin, the most well-known mycotoxin, is produced by several species of the fungus Aspergillus and contaminates corn, tree nuts, cottonseed and peanuts in the southern and western United States. The FDA limits aflatoxin levels in food and feed to 20 ppb, due to its carcinogenic capabilities. Aflatoxin, together with hepatitis C, is associated with high levels of liver cancer in Southeast Asia. Deoxynivalenol, a mycotoxin common in wheat and barley in the U.S. Midwest, is produced by several Fusarium species on grain crops, has immunosuppressive effects on humans, and induces feed refusal in animals. The FDA suggests levels of less than 15 ppm deoxynivalenol in finished products for human consumption.
Economic losses due to mycotoxins in the United States are estimated to be between $0.5 and $1.5 billion annually. Fungicides are only partially effective against mycotoxigenic fungi because such fungi are naturally tolerant to many fungicides, and because when stressed by fungicide applications, fungi can respond by producing more of the mycotoxin. Durable host plant resistance is not available, despite many years of intensive breeding. An alternative to these solutions would be a compound or a mixture of compounds that block mycotoxin biosynthesis, especially when mycotoxin levels can be high, even in asymptomatic nuts and grains.